Method of precipitating titanium compounds



Patented Sept. 1 1931 UNITED STATES PATENT OFFICE LONNIE w. RYAN, OF NIAGARA FALLS, NEW YORK, ASSIGNOR TO TITANIUM PIGKENT COMPANY, INC., 01 NEW YORK, N. Y., A CORPORATION OF MAINE METHOD OF PBECIPITATING: TITANIUM COMPOUNDS Ho Drawing.

My present invention relates to titanium compounds and methods for their economical manufacture, 1 which compounds have varied uses in the industrial arts, and more 5 particularly relates to improved methods for the economical production of an essentially pure titanium oxide pigment with the practical exclusion of all undesired impurities, especially ironcompounds, which pigment will be, exceptionally white in color, and will also possess increased hiding power when compared with other pigments now in use. My improved pigment product is also characterized by exceptional fineness,

smoothness and softness, which qualities render same highly useful and desirable when such products are employed as pigments in paints and for other purposes.

It is believed that the hiding power of titanium pigments is due, among other things, to the degree of dispersion of the individual particles. In the manufacture of composite pigments, i. e., those containing a basesuch as barium sulphate upon which the titanium compounds have been fixed, the hiding power has been developed to a high degree, apparently due to the dispersing efi'ect of the base and its preventing aggregationof the precipitated titanium particles. Such methods of producing composite titanium oxide pigments are set forth in U. S.

Louis E. Barton reissued Patent N 0. 14,289

of April 24, 1917 and in U. S. Louis E. Barton Patent No. 1,409,648 of March 14, 1922. Such bases contained in these composite titanium pigments may be termed insoluble dispersing agents.

I have discovered that, by using a mixture of an organic acid or an organic acid compound together with phosphoric acid or a phosphoric acid compound, in my pre ferred method of precipitation; of titanium from a solution containing same, by hydrolysis, there can also be obtained a titanium oxide of great hiding power and excellent color. Furthermore,precipitations of such desired character may be made even from titanium solutions containing a greater proportion of impurities usually found in titanium ores.

Application filed March 27, 192.3. Serial IEO. 265,214.

My improved method of precipitation to produce this essentially pure titanium oxide consists in the slow mixing together of a mineral acid solution of titanium and a hot dilute solution containing a mixture of an organic acid ororganic acid compound and. phosphoric acid or a phosphoric acid compound. Preferably this titanium solution is slowly added to the organic acid and phosphoric' acid solution. As an alternative method the reagents may-be added tothe A typical analysis is as follows Tit), 98.13% Fe O Trace 2 5--- Sulphuric anhydrlde 22% Titanium oxide of great hidingpower and excellent color may be produced by using both oxalic'acid and phosphoric acid.

These are not the only reagents which give satisfactory results but are named merel as an example. Other organic acids suc as tannic, citric and tartaric acids and their compounds may be used together with phosphoric acid and phosphoric acid compounds to produce the same results.

Havin described my improved product and briedy explained the general method of preparation, I shall now give in detail two examples, although I do not wish to be limited thereby. The examples are intended for illustrative purposes only, as the process is capableof considerable variation in yielding the product desired.

The most readily available titanium ore is ilmenite, or titaniferous iron ore, containing a of 52.7% titanium oxide (T and 47.3% ferrous oxide (FeO corresponding to a formula TiO FeO. enite usually contains small amounts of other oxides 'such as alumina, zirconia, silica, etc. Such an ore is brought into solution by any of the well known methods, such as, for example, by digestion with concentrated sulphuric acid .and subsequent treatment with water.

Such a solution prepared b me and des- V ignated (A) is analyzed as ollows:

Per cent litaniumoxide (TiO i 5.71

Ferrous oxide -.(FeO) l 5.24

- Alumina, zircoma, etc. (A1,O',,ZrO 0.66

' Sulphuric acid in combination titanous condition.

23 81 Uncombined sulphuricacidun 2.86

'- Before making the precipitation of titanium from such solution it is desirable to reduce all iron present in the solution to the ferrous condition. 1 This reduction may be accomplished by any of the well known .methods, such as by the introduction of metallic i-ron orzinc. In order to be sure that no ferric iron will be formed during precipitation I prefer to carry the reduction of the solution to the point'where it contains one or two grams per litre of, the titanium, calculated as titanium oxide, in the Ewazmple I .Having 'ven 3,680-pounds of the above solution (A there is. prepared a solution of 32.3 pounds of oxalic acid and 2.4 pounds of phos horic acid in 300 cubic feet of water and t e temperature brought to about. 98 C. The ilmenite solution (A) is then slowly added to the solution of ox- .alic and phosphoric acids during the course of one hour. Agitation is continuous'and the temperature is maintained about constant. By the time the solutions are thortion y other means from the mother liquor,

- hour.

a fihly mixed, about 95% of the titanium have been precipitated, substantially as a basic sulphate, in an extremely fine state of subdivision, but in such a form that :it settles Welland may be readily filtered and washed. A part of the phosphoric acid also combines with the titanium and occurs in 98 C. Thissolution, containing the oxalic acid and the phosphoric acid, is then slowly added .to the water during the course of one Agitation is continuous and the temperature 1s maintained about constant. B

about 95% of the titanium will have been precipitated, substantially as a basic sulphate,

in an extremely fine state of subdivision, but in such a form that it settles well and may be readily filtered and washed. A part of the phosphoric acid also combines with the titanium and occurs in the precipitate. After filtration or separation by other means from the mother liquor, the precipitate is calcined at a temperature of from '(00 to and a solution of phosphoric acid and an organic acidcompound at an elevated temperature. i

'3. In the precipitation, of titanium compounds by hydrolysis from amineral acid solution containing titanium, the step which consists in mixing said titanium solution and a solution of a pho horic acid compound and an organic acifi at-.an elevated temperature. 4. In the preci itation of titanium compounds by hydro ysis from a mineral acid solution containing titanium, the step which consists in mixing said titanium solution.

and a solution of a phosphoric acid compound and an organic acid compound at an elevated temperature.

5. In the precipitation of titanium compounds by hydrolysis from a mineral acid solution containing titanium, the step which consistsin mixing said titanium solution and a solution containing relatively small amounts of phosphoric acid and oxalic acid at an elevated temperature.

6.- In the preci itation of titanium compounds by hydro ysis from a mineral acid solution containing titanium, the step which consists in slowly mixing said titanium solution and a solution of phosphoric acid and an organic acid at an elevated temperature while agitating the mixture.

7. In the precipitation of titanium com: pounds byhydrolysis from a sulphuric acid solution containing titanium, the step which consists in mixing said titanium solution ganic acid at an elevated temperature. V

8. In the precipitation of titanium compounds by hydrolysis from' a sulphuric-acid solution containing titanium, the step which consists in said solution and the time the solutions are thoroughly mixe a solution containing relatively small 130 and a soluton of phosphoric acid and an ori menses amounts of'phosphoric acid and oxalic acid at an elevated temperature.

9. In the precipitation of titanium compounds by hydrolysis from a sulphuric acid 5 solution containing titanium, the step which consists in mixing said titanium solution and a solution of a phosphoric acid compound and oxalic acid at an elevated temperature.

'10., In the preparation of titanium compounds the steps which consist in mixing a mineral acid solution of titanium and a solution of phosphoric acid and an organic acidat an elevated temperature, separating the precipitate formed, and calcining same. 5 11.. In a preparation of titanium compounds the steps which consist in mixing a minerat acid solution of titanium and a solution of phosphoric acid and oxalic acid v at an elevated'temperature, separating the o precipitate formed, and calcining same.

12. In the precipitation of titanium compounds by hydrolysis from a, mineral acid solution containing titanium, the step which consists in adding said solution to a dilute :5 solution of phosphoric acid and an organic acid maintained at an elevated temperature.

13. In the precipitation of titanium compounds by hydrolysis from a mineral acid solution containingtitanium, the step which n consists in adding said solution to a dilute solution of phosphoric acid and an organic acid compound maintained tit-an. elevated temperature.

14. In the precipitation of titanium compounds by hydrolysis from a mineral acid solution containingtitanium, the step which consists in adding said solution to a dilute solution of phosphoric acid and oxalic acid maintained at about 98 (3. 0 15. In the precipitation of titanium compounds by hydrolysisfrom a mineral acid solution containing titanium, the step which consists in 'slowl adding said solution to a dilute solution 0 phosphoric acid and an or- 5 gan'ic acid at an elevated temperature, while agitating the mixture and maintaining the temperature substantially constant. 3

- LONNIE W. RYAN. 

